In recent years, thermoelectric conversion elements have drawn attention from the viewpoint of a reduction in CO2 and environmental protection. The use of the thermoelectric conversion elements allows conversion of thermal energy, which has been discarded until now to electric energy for reuse thereof. With one thermoelectric conversion element, the output voltage is low. Therefore, a plurality of thermoelectric conversion elements are usually connected in series to be used as the thermoelectric conversion module.
A general thermoelectric conversion module has a structure in which a large number of semiconductor blocks containing a p-type thermoelectric conversion material (hereinafter p-type semiconductor blocks) and a large number of semiconductor blocks containing an n-type thermoelectric conversion material (hereinafter n-type semiconductor blocks) are sandwiched between two heat exchanger plates. The p-type semiconductor blocks and the n-type semiconductor blocks are alternately arranged in the in-plane direction of the heat exchanger plates, and are connected in series with metal terminals disposed between the semiconductor blocks. Extraction electrodes are connected to both the ends of the semiconductor blocks connected in series.
The thermoelectric conversion module having such a structure has a structure such that a plurality of thermoelectric conversion elements each contains one p-type semiconductor block, one n-type semiconductor block, and terminals connecting the same are connected in series. The thermoelectric conversion element constituted by one p-type semiconductor block, one n-type semiconductor block, and terminals connect the same are connected in series is referred to as a π type thermoelectric conversion element in terms of the form.
In the above-described thermoelectric conversion module, when a temperature difference is given to the two heat exchanger plates, a potential difference occurs in each of the p-type semiconductor blocks and the n-type semiconductor blocks due to the Seebeck effect, and electric power may be extracted from the extraction electrode. The thermoelectric conversion module has been expected to be applied as, for example, wireless sensor nodes constituting sensor networks or the power supply source of various kinds of micro electric power electronic devices. As one of such applications, it has been considered to utilize the thermoelectric conversion module as the power supply of wearable electronic devices by attaching the thermoelectric conversion module to a human body, and generating electricity by differences in the body temperature and the outside air temperature. However, in such a use, there is a problem that when a temperature difference is small and particularly when the outside air temperature is high, sufficient output is not obtained.
A thermoelectric conversion module is known which utilizes the heat of vaporization of sweat supposing that the thermoelectric conversion module is attached to a human body. In such a thermoelectric conversion module, a film-like thermoelectric material is disposed on a plane, sweat is led to the front surface of the thermoelectric conversion module from the back surface thereof through a penetration hole formed in the bottom of an electrode portion, and the sweat is evaporated in the electrode portion, whereby a temperature difference is given to the thermoelectric material by a cooling effect due to the evaporation latent heat to generate electricity.
The followings are reference documents.    [Document 1] Japanese Laid-open Patent Publication No. 07-111345